1. Field of the Invention
The present invention relates to a game cassette unit suitable for application to a household game machine, and more particularly, it relates to an improvement for providing a game machine program (the so-called xe2x80x9cgame softwarexe2x80x9d) to the user at a low cost and in a short time.
2. Description of the Background Art
In order to utilize a well-known game machine which is suitable for family use, a separately marketed portable game cassette unit is generally attached thereto. The game cassette unit stores a ROM (unrewritable mask ROM) serving as a storage medium, in which a game machine program is written.
Another game machine comprises a CPU (microprocessor) for executing the game machine program written in the ROM of the game cassette unit attached thereto. Thus, the game machine user can amuse himself by playing the game directed by the game machine program.
In general, such a game cassette unit is marketed for each game, i.e., each game machine program, and the user can enjoy a desired game by purchasing the game cassette unit storing the game machine program therefor. In other words, a single game cassette unit generally corresponds to a single game.
In general, therefore, the user must newly purchase a game cassette unit every time a new game of interest to him is put on the market, disadvantageously with a great expense. This also leads to the problem of a high cost in manufacturing and selling on the side of the game supplier, with requirement for a long time up to supply of the game.
Further, manufacturing of such a game machine program is generally stopped after a certain period from the launch. If any user requires new shipment, therefore, the supplier must reproduce the closed game cassette unit. This also leads to a high production cost.
According to a first aspect of the present invention, a game cassette unit which is connected to a game machine having a CPU for game execution by a user comprising a memory for storing a program group including a game selection program and a plurality of game machine programs, and a plurality of decode data defining address conversion rules for the CPU for executing the programs belonging to the program group respectively, and a decode controller for executing address conversion on the basis of one data selected from the plurality of decode data. Each program belonging to the program group is capable of being executed by the CPU upon connection of the unit to the game machine, the game selection program is adapted to make the user select one of the plurality of game machine programs, the decode controller selects one of the plurality of decode data corresponding to the game selection program upon connection of the unit to the game machine for executing address conversion on the basis of the selected decode data thereby enabling the CPU to execute the game selection program, and the decode controller further selects one of the plurality of decode data corresponding to the game machine program selected by the user when the user selects one of the plurality of game machine programs during execution of the game selection program for executing address conversion on the basis of the selected decode data thereby enabling execution of the game machine program selected by the user.
According to a second aspect of the present invention, the decode controller comprises a power-on controller, a decode information loader and a decode part, the decode information loader, when one code of a plurality of codes for identifying the plurality of decode data respectively is inputted, selectively reads one of the plurality of decode data corresponding to the inputted one code and setting the same on the decode part, the decode part executes address conversion on the basis of the set decode data, the power-on controller inputs one of the plurality of codes for identifying one of the plurality of decode data corresponding to the game selection program in the decode information loader upon connection of the unit to the game machine, and the game selection program makes the CPU input one of the plurality of codes for identifying one of the plurality of decode data for the game machine program selected by the user in the decode information loader.
According to a third aspect of the present invention, the memory comprises a flash ROM, which rewritably stores the program group and the plurality of decode data.
According to a fourth aspect of the present invention, a special storage area of the flash ROM rewritably stores the plurality of decode data.
According to a fifth aspect of the present invention, the decode controller is formed by a semiconductor integrated circuit requiring no software.
The unit according to the first aspect of the present invention can store a plurality of game machine programs so that the user can select a desired one of the programs for executing the same. Thus, the unit can provide any game machine program to the user at a low cost in a short time.
In the unit according to the second aspect of the present invention, the decode controller comprises the power-on controller, the decode information loader and the decode part, whereby the unit enables the CPU to first execute the game selection program and to subsequently execute the game machine program selected by the user in a simple unit structure.
The unit according to the third aspect of the present invention, which rewritably stores a plurality of game machine programs, can provide any game machine program to the user at a lower cost in a shorter time. Further, it is possible to effectively utilize a game machine program stored in a conventional game cassette unit which has run out of stock.
In the unit according to the fourth aspect of the present invention, the special storage area of the flash ROM stores a plurality of decode data, whereby security for the game machine programs can be highly ensured.
In the unit according to the fifth aspect of the present invention, the decode controller is formed by the semiconductor integrated circuit requiring no software, whereby security for the game machine programs can be highly ensured.
Accordingly, an object of the present invention is to obtain a game cassette unit which can provide any game machine program to the user at a low cost in a short time.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.